Herpetafauna of Chiwaukee Prairie
by Eric Hileman
Scientific name: Emydoidea blandingii
Description: The Blanding’s turtle is a semi-aquatic turtle with a smooth, relatively high domed carapace (top portion of shell) length of 12.7-26.8cm (5-10.5 in.) long (not measuring curvature of shell). The carapace is black or brown with yellow spots or streaks, as is the upper portions of the head and neck. The lower jaw and throat is bright yellow. The plastron (bottom portion of shell) is hinged and is yellow with brown blotches around the perimeter of the shell.
Distribution and Habitat: Blanding’s turtles occur primarily in the great lakes region, but also extend west to Nebraska and east with isolated populations in s. New Hampshire, Massachusetts, and e. New York. In Wisconsin, Blanding’s turtles occur throughout much of the state excluding the north-central most regions. This turtle is primarily aquatic but can also be found on land. Preferred habitats include: open grassy marshes, mesic prairies, prairie potholes, ponds, and other slow moving shallow bodies of water with dense vegetation and soft bottoms.
Diet: Most feeding takes place underwater but may also occur on land. In aquatic environments crustaceans, snails, leeches, insects, small fish, frogs, tadpoles, and vegetation is consumed. On land earthworms, grubs, slugs, grasses and succulent vegetation may be fed upon. Prey animals taken on the shore are usually brought back to the water to be swallowed.
Reproduction and Development: Breeding occurs in spring but may occur as late as November. Gravid females nest in June or July traveling up to .6 miles from the water to find appropriate nesting sites. Ideal nest sites are open areas that receive plenty of sunlight and have a moist sandy soil substrate with good drainage. Females usually lay only one clutch per year consisting of 6-21 elliptical dull white eggs. Hatchlings (28–35mm carapace length) emerge after 50-75 days in August or September and usually stay hidden from view until they reach 150mm. After which, they may be observed basking or foraging for food. Sexual maturity is reached in 14-20 yrs and some may maintain their reproductive ability up to 70 yrs of age. It is estimated that a few individuals may live to 100 yrs old.
Status: Unfortunately, the wetlands in which this species is intimately linked with are being lost at an alarming rate throughout the state. Over 50% of Wisconsin’s wetlands have already disappeared due to development, leaving the Blanding’s turtle population in a designated threatened status by the Wisconsin Department of Natural Resources (WDNR). Habitat loss, traffic mortality, and predation on eggs from increasing nest predator populations, (primarily skunks, raccoons and foxes) thus creating a lack of juvenile recruitment, have all been indicated as major causative sources of the turtle’s population decline. All is not lost however. With the preservation of wetland habitats (such as those found within the Chiwaukee prairie), adjacent upland corridors and nesting sites, this species may once again flourish and prosper.